Rheostat



(No Model.)

J. B. LYON. RHEOSTAT.

No. 515,241. Patented Feb. 20, 1894.

.7071: B. Z yon/ BY ITTOIMEY.

UNITED STATES PATENT OFFICE.

JOHN B. LYON, OF BROOKLYN, NEWV YORK, ASSIGNOR TO THE LAW BATTERY COMPANY, OF NEW JERSEY.

RH EO STAT.

SPECIFICATION forming part of Letters Patent N0. 515,241, dated February 20, 1894.

Applicationfiled December 22, 1891. Serial No. 415,879. (No model.)

To all whom it may concern:

Be it known that I, JOHN B. LYON, a citizen of the United States, residing in Brooklyn, county of Kings, and State of New York, have invented certain new and useful Improvements in Rheostats, of which the following is a specification.

This invention relates to rheostats or electrical resistances especially adapted for use in circuits where very delicate variations in the strength of the current are required; such, for instance, as are required for medical purposes. The best form of rheostat for such purposes is known as the water or liquid rheostat, in which the current is passed from one electrode through the liquid to the other electrode and the current varied either by the amount of surface of the electrode immersed, by the distance between the electrodes, or by both combined.

The object of my invention is to provide a rheostat by means of which the most delicate variations in the current may be obtained by a simple and convenient apparatus.

A further object of the invention is to provide a construction in which the liquid or other conducting medium may be readilyemp tied and renewed and in which all of the parts of the apparatus may be easily separated for repairs and cleaning.

The invention consists in the construction which will hereinafter be described and claimed.

In the accompanying drawings: Figure 1 represents a perspective view of the apparatus complete. Fig. 2 represents a transverse central vertical section of the same; Fig. 3 a detail section of the electrodes. Fig. etis amodification of a detail.

Referring to the drawings by letter, A represents a rigid frame of metal or insulating material, the base of which is an oblong or elliptical shape; it is provided on each side with a flaring upright or standard a, the purpose of which is to'support the electrodes and protect the tray or vessel as hereinafter described. The ends of the frame A are provided with low flanges a which also serve to protect or hold the tray in place.

13 represents a tray or vessel preferably of oblong, oval or elliptical shape and also preferably made of an insulating material, such as glass or hard rubber. This tray contains normally, water, acidulated water, a semi solid material, pulverized carbon or any other material desired which is displaceable or unstable; ordinarily pure water will be used. The vessel is filled nearly full of this material. In the upper end of the standards a are supported two shafts b b which stand directly above the edges of the vessel and occupy parallel planes and have their bearings side by side in the said standards. The bearings are preferably formed in blocks of insulating material, but any other method of insulating the adjacent bearings from each other will suiiice. One pair of ends of these shafts is connected respectively with the wires 12 b of an electric circuit. In the bearing of the shaft 1) there is a coil spring 11 which surrounds the shaft and presses at one end against the bearing and at the other end against a collar or sleeve upon the shaft. This tends to force the shaft in a longitudinal direction and prevent its turning. The other pair of ends of these shafts project beyond their bearings and carry small worm gears 71 b respectively.

b is tight upon the shaft and b is loose, but may be locked to the shaft at will by means of the set screw b which is connected with a crank b tight upon the shaft. By turning this screw down until it enters a notch on the wheel the crank and wheel are locked together. This wheel b is provided with teeth on a portion only of its periphery so that when it has been turned to either extremity of its teeth it will serve asa lock to prevent the further movement of the shaft.

1) represents a short shaft mounted in suitable brackets connected with the standard at below the two gears b b. It is provided with a hand wheel 11 by which it may be turned and with right and left hand threads or worms which respectively engage with the gears 19 b. By rotating this shaft, the two shafts Z2 b may be rotated in opposite directions, or if the gear I) is unlocked from its shaft, the shaft b may be rotated while the other shaft remains still. This form of gear may be varied at will. I may for instance use spur gearing entirely and mount the power shaft parallel to the shafts b b, as shown in Fig. 4, but in order to get a sufficiently slow movement of the shafts b b with a given movement of the power shaft and with simple gearing I prefer the form shown and described.

Upon the shafts b b are mounted respectively carbon plates 0 C. These plates are triangular in shape and provided along one edge with a cylindrical enlargement through which the shaft passes. The hole for the shaft is eccentrically located, it being nearest the outer side of the cylindrical edge; the plates are mounted to turn with the shafts. The shape of the plates is that of a scalene triangle and their apexes are on the opposite sides of the central line of the apparatus as shown in Fig. 2. The points of the plates are provided with sponge tips a which are secured in perforations c and project through the inner or lower face of the plates in positions at right angles to their faces. When the plates stand in parallel vertical planes as shown in Fig. 3, the sponges pass by the opposite plates and therefore do not prevent their coming together. These sponges when filled with water offer great resistance to the passage of an electric current and the greatest resistance which the apparatus is capable of ofiering to the flow of the current is when the plates are in substantially the same horizontal plane and the sponge tips on each touch the liquid. The current passes from the wire b into shaft 1) thence to the electrode 0, through the liquid in the vessel B to the electrode 0, the shaft 1) and the wire b The operation of the apparatus is as follows:

I To get the weakest possible current, the wheel b is turned until the electrodes are brought into a substantially horizontal position so that only the sponge tips are in contact with the water; to increase the flow of current the wheel 6 is turned in the opposite direction and both electrodes are lowered gradually, the apexes striking the Water first and as they lower they not only approach each other, but simultaneously increase the surface of the electrodes in contact with the water. The current increases in proportion to the speed with which the electrodes approach. When in their horizontal position it will be seen that the carbons themselves will not be in contact at any point, but when lowered to the full extent as shown in Fig. 3, the adjacent faces of the electrodes are squarely in contact. When in the latter position the resistance is all cut out and the circuit gets the full current. It will be observed that by reason of the slow movement which it is possible to impart to the shafts by the gearing described and of the gradual increase of electrode sur- 7o face in the liquid, the resistance is so regularly out out that when the electrodes come together there is no impulse to the current and consequently the patient being treated with the current would not receive a shock when the electrodes come together. Another method of operating the apparatus is to allow one of the electrodes to remain stationary in a certain position and to move the other one with respect to it. This is done by rotating the shafts until the electrode 0 occupies a position in which it isdesired to maintain it, and loosening the set screw If; this will free the gear I) and allow the spring Z2 to hold the shaft 12 and consequently the electrode 0' in its set position. When the wheel 6 is now turned the shaft 1) alone moves and the delicacy of the apparatus is doubled.

The liquid used in apparatus of this kind soon becomes impure by reason of the chemical changes brought about by the current and by evaporation and dust, and therefore has to be emptied and renewed quite often. It therefore becomes necessary to provide convenient means for performing this operation. I do this by simply turning the electrodes in their horizontal position and drawing the vessel B out from under them. It may then be emptied, cleaned, filled and replaced without any difiiculty and in a short time.

Having thus described my invention, I claim- 1 A rheostat consisting of the combination of a resistance medium and a pair of electrodes geared together and movable with respect to each other.

2. A rheostat consisting of a vessel containing a displaceable resistance medium, such as liquid or powder, and a pair of electrodes geared together to be simultaneously movable with respect to each other.

3. In a rheostat the combination with a displaceable resistance, of a pair of electrodes triangular in shape mounted upon axes above said resistance, the axes being along one of their sides, and operating mechanism for swingingsaid electrodes apex first toward and away from each other through the resistance for the purpose set forth.

4. In a rheostat the combination of a liquid or other displaceable resistance, two movable electrodes and means for lockin g and unlocking one electrode to make it stationary or movable at will for the purpose set forth.

5. In a liquid rheostat a pair of electrodes pivoted to swing toward and away from each cated at their free ends, the sponge tips occupying diflerent planes for the purpose set forth.

In witness whereof I have hereunto signed 15 my name in the presence of two subscribing witnesses.

JOHN B. LYON.

Witnesses:

FRANK S. OBER, WM. A. RosENBAuM. 

